Best CSS gradient, shadow, radius, transition and transform WYSIWYG editor I’ve seen to date. You can create instances for :hover, :active, custom class states. You can also work with transitions and transforms.

Picked by Jake Bresnehan.

Modal dialogs built out of pure CSS. You know, if you can’t avoid it ;-)

Nice demo of what different properties of CSS background do.

Rodney Rehm for Smashing Magazine:

This article is packed with a number of quirks and issues you should be aware of when working with CSS3 transitions. Please note that I’m not showing any workarounds or giving advice on how to circumvent the issues discussed. Alex MacCaw has already written a very insightful and thorough article on “All You Need to Know About CSS Transitions.”

Super-smooth CSS transitions & transformations for jQuery.

You may also like Animate.css.

Transit link via Aleš Skotnica

Piotr Walczyszyn created nice tool in Responsive Inspector (Chrome Web Store link).

I think CSSmatic is the best gradient and noise generation tool right now.

Blueprints by Codrops starting with full width image slider and elastic content slider.

fast and lightweight (3KB) javascript utility that detects browser and pixel ratio, allowing you to serve conditional JavaScript and CSS files. Rebuilt from it’s jQuery predecessor, it’s now 50% faster.

Check browser support for CSS, HTML, JS and SVG with this site.

Two tutorials by Codrops: Understanding the CSS Clip Property and Putting CSS Clip to Work.

Another example of what I call primary research in HTML5, CSS & JavaScript:

FFF is a collection of interactive experiences. Each experience has its own unique design and functionality. All the experiences are created in HTML5, the site works beatifully on both desktop and tablet.

Good article by Alex MacCaw.

Thorough tutorial for this new CSS layouting by Greg Smith.

Nice overview of the possibilities of using CSS3, SVG, Canvas and WebGL for animation today.

Primary research in the field of CSS by Hugo Giraudel over at Codrops. It may have no direct implications for your work now but someday it may resurface as uniquely useful.

Nice tutorial over at CSS-Tricks.

A marketplace for premium Bootstrap themes and templates.

Nice things happen when standards come up.

Nice overview how to code for high pixel density (160 PPI and up) displays.

Via @daeltar